Experimental Leukemia Drug Shows High Response Rates

Treatment shows clinically meaningful reduction in the number of cancer cells in patients with relapsed or refractory chronic lymphocytic leukemia.

A novel treatment for a hard-to-treat form of leukemia showed high response rates during a recent phase 2 trial.

Treatment with venetoclax showed a clinically meaningful overall response rate of 79.4% in patients with relapsed or refractory chronic lymphocytic leukemia (CLL) with 17p deletion.

Furthermore, 7.5% of patients achieved a complete response with or without complete recovery in the bone marrow.

The investigational small molecule selectively binds and inhibits to the BCL-2 protein that is vital in apoptosis. Researchers believe that blocking BCL-2 may restore the signaling system that instructs cancer cells to self-destruct.

The protein has also been linked to resistance in some blood cancers, and is expressed in CLL and non-Hodgkin’s lymphoma. The main study cohort enrolled 107 patients with relapsed or refractory disease, all of whom but one had 17p deletion.

Of the patients treated with venetoclax, 18 (17% of total patients, 21% of responders) showed no detectable cancer (MRD-negative) in a specific test. Of these 18 patients, 6 showed no detectable cancer in a bone marrow assessment.

At one year, 84.7% of all responses and 94.4% of MRD-negative responses maintained, with a progression-free survival rate of 72% and an overall survival rate of 86.7%.

The most common grade 3-4 adverse events were low white blood cell count (40%), low red blood cell count (18%), and low platelet count (15%).

“The high response rates, including complete responses and duration of response, demonstrate the potential of venetoclax to help people with this hard-to-treat type of leukemia,” said Sandra Horning, MD, Genentech chief medical officer and head of Global Product Development. “This is a patient population that has very few treatment options, and we are working with AbbVie to bring this new option to people as quickly as possible.”